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<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
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<body>
    <script>
        function sum(n) {
            let sum = 0;
            // let number = 0;
            for (let i = 1; i <= n; i++) {
                let number = Math.pow(2, i - 1);
                sum = sum + number;

            }
            return sum;
        }

        // console.log(sum);
        let t = sum(64) / 2000000;
        console.log(t);
    </script>
</body>

</html>